Cmpi and reflux - how do I know?!

Probably a stupid question, but my 16 week old lo put onto neocate last week as suspected cmpi.I was very unconvinced, just thought it was reflux but ranitidine stopped working. His ranitidine was put up to max dose a week ago and neocate introduced 5 days ago.Reflux still terrible, struggling to feed and lots of sick for a couple of days (although possibly sick has calmed down). But, his baby acne suddenly cleared within 2 days, as has his small patch of eczema.Does this mean it is likely to be cmpi? Am I likely to see an improvement in his reflux and if so, in what way? Thanks.